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  1. Free, publicly-accessible full text available April 20, 2024
  2. null (Ed.)
  3. The majority of 2D IR spectrometers operate at 1-10 kHz using Ti:Sapphire laser technology. We report a 2D IR spectrometer designed around Yb:KGW laser technology that operates shot-to-shot at 100 kHz. It includes a home-built OPA, a mid-IR pulse shaper, and custom-designed electronics with optional on-chip processing. We report a direct comparison between Yb:KGW and Ti:Sapphire based 2D IR spectrometers. Even though the mid-IR pulse energy is much lower for the Yb:KGW driven system, there is an 8x improvement in signal-to-noise over the 1 kHz Ti:Sapphire driven spectrometer to which it is compared. Experimental data is shown for sub-millimolar concentrations of amides. Advantages and disadvantages of the design are discussed, including thermal background that arises at high repetition rates. This fundamental spectrometer design takes advantage of newly available Yb laser technology in a new way, providing a straightforward means of enhancing sensitivity.

  4. Abstract

    Actinide materials have various applications that range from nuclear energy to quantum computing. Most current efforts have focused on bulk actinide materials. Tuning functional properties by using strain engineering in epitaxial thin films is largely lacking. Using uranium dioxide (UO2) as a model system, in this work, the authors explore strain engineering in actinide epitaxial thin films and investigate the origin of induced ferromagnetism in an antiferromagnet UO2. It is found that UO2+xthin films are hypostoichiometric (x<0) with in‐plane tensile strain, while they are hyperstoichiometric (x>0) with in‐plane compressive strain. Different from strain engineering in non‐actinide oxide thin films, the epitaxial strain in UO2is accommodated by point defects such as vacancies and interstitials due to the low formation energy. Both epitaxial strain and strain relaxation induced point defects such as oxygen/uranium vacancies and oxygen/uranium interstitials can distort magnetic structure and result in magnetic moments. This work reveals the correlation among strain, point defects and ferromagnetism in strain engineered UO2+xthin films and the results offer new opportunities to understand the influence of coupled order parameters on the emergent properties of many other actinide thin films.